Mechanical seals are structures designed to prevent leakage between a rotating shaft and its housing under conditions of extreme pressure, shaft speed and temperature. Typically mechanical seals comprise a stationary part and a rotating part. Mechanical seals are commonly used in pumps. A critical part of a mechanical seal is the seal faces. The seal face is the surface or point where the rotating part of the mechanical seal and the stationary part of the mechanical seal meet and interact. Because of the harsh conditions encountered at the seal faces a wide variety of materials are chosen for the seal faces. Commonly used materials are hardened steels, aluminum oxide, tungsten carbide, and silicon carbide. The precise material chosen will depend on the application and economic considerations.
The stationary part of the mechanical seal and the rotating part of the mechanical seal may be manufactured from the same material or different materials. A commonly used pairing for demanding applications is silicon carbide against silicon carbide or silicon carbide against graphite. The silicon carbide employed in these known applications is generally a sintered form or a reaction bonded form depending upon the particular application. Although these silicon carbide products accomplish the goal of creating a seal, they are expensive and time consuming to manufacture. In addition, these known mechanical seals are often prone to rapid failures that can quickly damage the pump or components of the device employing the mechanical seal.
It is an object of the present invention to provide a mechanical seal structure wherein in at least one seal face of the mechanical seal structure is a ceramic layer prepared by thermal spray techniques.
It is a further object of the present invention to provide a mechanical seal structure wherein both seal faces of the mechanical seal structure are a ceramic layer prepared by thermal spray techniques.
It is still a further object of the present invention that the substrate of the mechanical seal is a more compliant material such as graphite than the ceramic seal face layer to delay catastrophic seal failure and potential catastrophic damage, to the device employing the mechanical seal if and when the ceramic seal face fails or malfunctions.
It is yet another object of the present invention to provide a mechanical seal that is inexpensive to manufacture and can be manufactured in a relatively short time period.
The above-identified objects and other objects of the present invention are achieved by the subject matter characterized by the features of the claims.